Exemplary embodiments of the present invention relate to an image encoding method using a Binary Partition Tree (BPT), and more particularly, to an image encoding method using a BPT in which encoding is performed based on a residual pixel value between frames when variable size partition is performed on a macro block using a BPT within a P or B frame.
In general, in processing a P or B frame in the field of image compression, a method of partitioning a macro block and processing the partitioned macro blocks is various.
First, two tasks are performed if a macro block is partitioned and inter-frame prediction is performed on the partitioned macro blocks.
The first task is a motion vector value processing task of searching for a macro block having the most similar pixel value to a specific macro block and calculating a difference between the positions of the macro block having the most similar pixel value and the specific macro block. The second task is a motion compensation task of calculating a deviation between the pixel values of a macro block to be compressed and a target macro block to be compared.
The motion compensation task is advantageous in that target information to be compressed can be reduced and a compression effect can be increased because only the deviation between pixel values is compressed.
Meanwhile, in the prior art, inter-frame prediction is performed by partitioning the size of a macro block within a P frame into fixed sizes, such as 16*8, 8*16, 8*8, 4*8, 8*4, and 4*4, starting from 16*16. If macro block partition is performed in a variable size manner as described above, a Peak Signal to Noise Ratio (PSNR) value can be maintained and a compression ratio can be improved by about 3.4% to 24.4%.
In the variable size partition of a macro block according to a BPT method, however, there is a problem in that the encoding speed is decreased because a computational load necessary to calculate a reference value is great.
A related prior art includes Korean Patent Laid-Open Publication No. 2010-0081974 (Jul. 16, 2010), entitled ‘A Method and An Apparatus For Processing A Video Signal’.